L2 - Pulmonary & Systemic Circulation

Question 1

what is an end artery?

Answer 1

final branches of artery exclusively supplies area tissue
the cells of this tissue will die if the end artery is blocked e.g. myocardial infarction

Question 2

what is anastomosis?

Answer 2

linking blood vessels present which connect different vessels (natural ‘bypass’)

Question 3

what are the three types of arteries?

Answer 3

• elastic = conducting
• muscular = distributing
• arteriole = distributing

Question 4

what are the capillaries?

Answer 4

the site of exchange with tissues

Question 5

what are the three types of veins?

Answer 5

• venules
• small veins
• medium or large veins

Question 6

what is the structure of blood vessels?

Answer 6

outer layer - tunica adventitia (collagen fibres)
middle layer - tunica media (elastic tissue and smooth mucles)
inner layer - tunica intima (endothelium and basement membrane)

Question 7

describe elastic arteries

Answer 7

largest -aorta, pulmonary arteries, immediate branches
3 layers
middle layer - elastin > muscle

Question 8

describe muscular arteries

Answer 8

smaller arteries and arterioles - need to alter size and lumen to meet body needs
3 layers
middle layer - muscle > elastin

Question 9

give the structure of capillaries

Answer 9

arterioles lead into capillaries - 3 layers gradually disappear until just inner layer
single layer of flattened endothelial cells + basement membrane

Question 10

discuss the capillaries network/plexus

Answer 10

• pattern of capillary bed varies
• related to tissue function
• blood flow through capillaries is regulated by muscle contraction

Question 11

give 3 facts about continuous epithelium capillaries

Answer 11

• most common
• complete lining of endothelial cells
• least permeable

Question 12

give 3 facts about fenestrated capillary

Answer 12

• endothelial cells contain pores
• more permeable
• found in small intestine mucosa and kidney

Question 13

give 4 facts about discontinuous/sinusoid capillary

Answer 13

• endothelial cells contain large pores
• incomplete basement membrane
• allows large molecule & blood cells to pass
• found in bone marrow, liver and spleen

Question 14

what is the difference between the 3 layers of arteries vs veins?

Answer 14

veins middle layer is thinner and outer layer is thicker than arteries
veins are collapsible

Question 15

what are dural venous sinuses?

Answer 15

skull, smooth muscle replaced by fibrous tissue - fixed

Question 16

what areas are valves NOT present in medium veins?

Answer 16

• head
• vertebral column
• several viscera

Question 17

what are the 2 ways of blood flow though the veins?

Answer 17

1. muscle pump
   - limbs
   - compressive
   - valves
2. veins beside artery within common sleeve of connective tissue - arterial pulsation compresses vein against sleeve

Question 18

what are varicose veins?

Answer 18

dilated, tortuous, elongated veins

Question 19

what is different about the foetal circulation system?

Answer 19

lungs not functional before birth - blood bypasses lungs (foramen ovale + ductus arteriosus) - ductus venosus bypasses the liver - oxygen exchange at placenta via umbilical vein and arteries

Question 20

describe the closure of the ductus arteriosus

Answer 20

pulmonary trunk -> aortic arch -> ligamentum arteriosum